/* Copyright  2009
   @Author
   Richard Changde Yin            e-mail yinchangde@hotmail.com

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; version 2 of the License.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software
   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA */
   
/**
 * filename: @item/null.h
 */ 
#ifndef COLLAPSAR_ITEM_NULL_H
#define COLLAPSAR_ITEM_NULL_H

class Item_null :public Item_basic_constant
{
public:

  Item_null(char *name_par=0)
  {
    maybe_null= null_value= true;
    max_length= 0;
    name= name_par ? name_par : (char*) "NULL";
    fixed= 1;
    collation.set(&my_charset_bin, DERIVATION_IGNORABLE);
  }
  enum Type type() const { return NULL_ITEM; }
  
  bool eq(const Item *item, bool binary_cmp) const;
  
  double val_real();
  
  int64_t val_int();
  
  String *val_str(String *str);
  
  my_decimal *val_decimal(my_decimal *);
  
  int save_in_field(Field *field, bool no_conversions);
  
  int save_safe_in_field(Field *field);
  
  bool send(Protocol *protocol, String *str);
  enum Item_result result_type () const { return STRING_RESULT; }
  
  enum_field_types field_type() const   { return COLLAPSAR_TYPE_NULL; }
  
  bool basic_const_item() const { return 1; }
  
  Item *clone_item() { return new Item_null(name); }
  
  bool is_null()     { return true; }

  virtual void print(String *str, enum_query_type);

  Item *safe_charset_converter(const CHARSET_INFO * const tocs);
  
  bool check_vcol_func_processor(unsigned char *)
  { return false; }
};

class Item_null_result :public Item_null
{
public:
  Field *result_field;
  
  Item_null_result() : Item_null(), result_field(0) {}
  
  bool is_result_field() { return result_field != 0; }
  
  void save_in_result_field(bool no_conversions)
  {
    save_in_field(result_field, no_conversions);
  }
  bool check_vcol_func_processor(unsigned char *)
  { return true; }
};

#endif /* COLLAPSAR_ITEM_NULL_H */
